The evolution of haemoglobin gene loci in amniotes [article]

Vidushi S Patel, University, The Australian National, University, The Australian National
2018
The genes in alpha ({u03B1})- and beta ({u03B2})- globin clusters constitute a functional haemoglobin molecule, crucial for oxygen transportation. In most fish and amphibians, {u03B1}- and {u03B2}-globin genes are located together, whereas in amniotes (birds and mammals), there are two distinct clusters. Several complex models have been proposed to explain the evolution of these gene clusters. However, there was a lack of data for key positions in amniote phylogeny to discern which one was most
more » ... which one was most parsimonious. Therefore, the main aims of this project were to characterise {u03B1}- and {u03B2}-globin clusters and their regulatory regions in a monotreme Ornithorhynchus anatinus (Australian duck-billed platypus) and two reptilian species Pogona vitticeps (Australian bearded dragon) and Anolis carolinensis (green anole lizard), to gain insight into globin loci evolution. This thesis is presented as a collection of research papers covering each topic, and a review and discussion that summarises my research. The first paper (Chapter 2) reports a comprehensive study on the characterisation, expression and evolution of {u03B1}- and {u03B2}-globin gene clusters in the platypus, using a combination of molecular and bioinformatics approaches. The most important findings from this work leading to the development of a new and simple model for globin gene evolution concerned the discovery of a {u03B2}-like globin gene within the a-globin cluster and genomic context analysis of {u03B1}- and {u03B2}-globin clusters across vertebrates. I showed that the amniote a-globin cluster is in fact the same as the a-{u03B2} cluster found in fish and amphibians, and both clusters share common flanking genes (C16orf35 and LUC7L). I proposed a transposition model in which a copy of {u03B2}-globin gene was inserted into a cluster of olfactory receptors (flanked by RRMl, CCKBR and ILK) in the ancestor of amniotes, thus originating the amniote {u03B2}-globin cluster. To elaborate this model further, my second paper (Chapter 3) reviews some events t [...]
doi:10.25911/5d63bfdb02cfa fatcat:2v2jviadvbcuzem2xkfyyphvju